What is the point of the diamond operator (<>) in Java 7?

Question

The diamond operator in java 7 allows code like the following:

List list = new LinkedList<>();

However in Java 5/6, I c

Answer 1

This line causes the [unchecked] warning:

List list = new LinkedList();

So, the question transforms: why [unchecked] warning is not suppressed automatically only for the case when new collection is created?

I think, it would be much more difficult task then adding <> feature.

UPD: I also think that there would be a mess if it were legally to use raw types 'just for a few things'.